Transmitting system



I. F. BYRNES. 1,857,137

TRANSMITTTNG SYSTEM May 10, 1932.

Filed "March 27. 1928 $43! n IL IF H a: J graz m Invent or:

Irving Byrnes,

His Attorney.

r so

Patented May 10, 1932 UNITED STATES IRVING- F. BYRNES, OF SGHENEGTADY, NEW YORK, ASSIGNOR T GENERAL PATENT OFFICE:

. -GOMPAITY, CORPORATION OF NEW YORK TRANSMITTING sYsTnM .with particularity in the appended claims.-

My invention itself, however, both as to its organization and method of operation, to-

gether with further objects and advantages thereof may best be understood by reference to the following description taken in connection with the accompanying drawing in which the single figure represents one embodiment of my invention. 1

Referring to the drawing I have shown a transmitting system employing electron discharge devices 1 and 2, the former of which is connectedto produce high frequency oscillations which are amplified by the device 2 l c. '1 and supplied through a suitable coupling device 3 to an output circuit which may comprise the 'usual. radiating or antenna sys- The oscillatorl comprises an anode 5 cathode 6, control electrode 7 and an additional screening electrode 8 which is interposed. between the control electrode 7 and the anode 5. 10 represents the usual oscillatory circuit, one side of which is connected through a blocking condenser 11 to the anode 5 and the other side of which is connected to the grid 7 and also, through cou- 13 of the discharge device 2. The electron discharge amplifier2 is similar to the device 1 and comprises the anode 14, cathode 15, control electrode 13 and the additional screeningv electrode 16, which is interposed between theanode 14 and the control electrode 13. i4 a The cathodes 6 and 1Q-are supplied with heating current from a source 17 through a suitable cathode transformer 18 and conducpling condenser 12, to the control electrode Application filed Mar-ch 2'7, 1928. Serial K0. 265,176.

tors 19. The anode circuit of the device 2 comprises the primary winding of coupling transformer 3, source of potential 2lfi'key 21 and the cathode conductors 19. The anode 5 of the device 1 is supplied with energy from the source 20 through radio frequency choke coil 22. The circuits of the control electrodes of the devices 1 and 2 extend through suit-" able choke coils and grid leak resistances 29 and 30, and 31 and 32 respectively to the chopper 23 and thence through key 21 to the cathode circuit 19. The screening electrode 8 of the device 1 is connected through resistance 2 1 to the positive side of the source of potential 20 and similarly the screening electrode 16 of the device 2 is connected through resistance 25 to the positive side of 4 the source of potential 20. By-pass capacitors 26 and 27 are connected between the cathode circuit and the conductor leading to each of the electrodes 8 and 16 for the purpose of conducting high frequency currents from these electrodes to the cathode circuit; In the operation 'of the system as thus described the devices 1 and 2 op'eratein a manner similar to the operation of three element devices of ordinary construction, the device 1 producing high frequenc oscillations which are suppliedfrom one side of the oscillatory circuit 10 through coupling capacitor 12 to the control electrode 13 of the device 2. This current,is then am lified by the device 2 and is supplied throng the output coupling device 3 to the radiating system 4. For the purpose of transmitting interrupted continuous waves the short circuiting switch 28 will be opened and the chopper 23 will be rotated at suitable speed as by an electric motor. To transmit continuous waves the switch 28 will be closed.

In either case interruptions in the i transmitted energy in accordance with desired signals may be effected by the key 21.

I have found that by the use of the devices l 1 and 2 having the additional screeningelem trodes 8 and 16, which are located between the anode and control electrode of each of these evices and which are maintained at a high positive potential, as for example in the neighborhood of one-quarter or one-third of the anode potential, the eflect of impedance variations in the antenna circuit upon the frequency of the oscillatory circuit 10 is reduced and that a more constant frequency at any point within the range of frequencies for which the system is adapted to operate may be maintained and this without any additional adjustment of the circuits for operation at different points within this range. While I have mentioned one-third or one-quarter of the anode voltage as the potential which is normally impressed on the additional electrode I do not wish to be limited thereto since this value may vary depending upon the construction of the electrodes. It is desirable that this positive voltage be as great as possible Without causing overheating of the electrodes although any suitable positive potential may be used.

The advantage resulting from the use of the additional electrodes is increased by the use of resistances 24 and 25, each of which is connected in series with the circuit of one of the electrodes. The operation of these resistances is as follows. Normally sufficient current will flow from the additional elec trodes through the respective resistances to reduce the voltage existing between the additional electrode and cathode to about onethird or one-quarter of the voltage of source '20. If, then due to a change in impedance of the output circuit an impedance variation in the tube occurs such as would otherwise affect the oscillatory circuit, a change in the magnitude of current flowing in the resistances 24 and 25 will take place. If the tube impedance increases this current will de-' crease thereby causing an increase in potential on the additional electrode and a compensating effect upon the impedance. Similarly, if the tube impedance decreases the current in resistances 25 and 24 will increase thereby producing a decrease in voltage on the screening electrode and a compensating effect upon the impedance.

I am, of course, familiar with the use of four element electron discharge devices of the type which I have described for different purposes, as for example, for the purpose of preventing regeneration, such a system being described in Patent No. 1,547,153 to A. W.

Hull, issued July 21, 1925. I believe howi be limited thereto, since many modifications,

both in the circuit arrangement and in the instrumentalities employed, may be made without departing from the spirit and scope of my invention as set forth in the appended claims.

lVhat I claim as new and desire to secure by Letters Patent of the United States is:

1. In a radio signaling system, an electron discharge oscillator, an electron discharge amplifier for the oscillations produced by the oscillator, both said amplifier and oscillator comprising an anode, a cathode and a control electrode, an oscillatory circuit connected between the anode and control electrode of said oscillator, an antenna circuit associated with the anode of said amplifier, and means for preventing impedance variations of said antenna circuit from affecting the frequency of oscillations produced by said oscillatory circuit, comprising an additional screening electrode interposed between the anode and control electrode of both said amplifier and oscillator and means for maintaining said additional electrode at a positive potential with respect to the cathodes.

2. In a radio signaling systein, an electron discharge oscillator, an electron discharge amplifier for the oscillations produced b the oscillator, both said amplifier and oscil ator comprising an anode, a cathode and a control electrode, anoscillatory circuit connected between the anode and control electrode of said oscillator, an antenna circuit associated with the anode of said amplifier and means for preventing the changin impedance of said antenna circuit from a ecting the frequency of oscillations produced by said oscillatory circuit, comprising an additional screening electrode interposed between the anode and control electrode of both said amplifier and oscillator, means for maintaining said additional electrode at a, ositive potential with respect to the catho es and a resistance in circuit with each of said additional electrodes whereby the otential on each of said electrodes is varie in response to variations in impedance between the anode and cathode.

3. In a high frequency signaling system, an electron discharge oscillation generator comprising an electron discharge device having an anode, a cathode and a control electrode, an oscillatory circuit connected between said anode and control electrode, a load circuit subject to impedance variations coupled to said oscillatory circuit whereby oscillations are excited in said oscillatory circuit and supplied to said load circuit, said oscillations having a. frequency dependent upon the constants of said oscillatory circuit, and means for reducing the effect of impedance variations upon the frequency of oscillations produced, said means comprising a screening electrode interposed between said anode and control electrode, means for maintaining said screening electrode at ahi h positive potential with respect to said oat ode and a by-pass condenser connected between said screening electrode and said cathode.

In witness whereof I have hereunto set my hand this 26th day of March, 1928.

IRVING F. BYRNES. 

